Apparatus for uniform distribution of divided solids



Feb. 10, 1-959 A. FISCHER 2,873,037

APPARATUS FOR UNIFORM DISTRIBUTION OF DIVIDED souns Filed Dec. 13,1954

FIG. I

RIGHT HALF OF STOKER ELEEQfiYILELELE.

FIG. 2

LEFT HALF OF STOK INVENTOR ADALBERT FISCHER ATTORNEY United States Patent APPARATUS FOR UNIFORM DISTRIBUTION OF DIVIDED SOLIDS Adalbert Fischer, Stuttgart-Bad Cannstatt, Germany, as-

signor to Kohlenscheidungs-Gesellschaft m. b. H., a corporation of West Germany Application December 13, 1954, Serial No. 474,901

9 Claims. (Cl. 214-17) The invention relates to an apparatus for the uniform distribution of divided material of diiferent sizes as the material is discharged into a container across the length thereof. The invention is particularly applicable to feeding coal of various sizes to stokers of the travelling grate type.

Coal as received from the mine for burning on travelling grate stokers usually contains a large percentage of fine screenings or slack, the remainder consisting of various lump sizes up to 1" nut size. As this coal is being discharged into the stoker hopper the coal tends to segregate, the fines and smaller particles forming the center of the pile whereas the larger sizes tending to roll oif toward the periphery of the coal pile thus being formed.

Consequently the distribution across the stoker width becomes uneven especially as to density of the coal bed encouraging the formation of blow holes. It is therefore of utmost importance in the operation of travelling grate stokers to distribute the coal uniformly, both with respect to its quantity as well as with respect to its particle sizes, across the width of the stoker grate for achieving complete combustion with a minimum of excess air. Attempts have been made to accomplish this object and to prevent segregation of the coal as to size upon introduction into the stoker hopper from one or more narrow coal chutes, by making use of a box divided into compartments and open at the top and bottom and extending over about half of the width of the grate. This box was then pulled back and forth between the discharge chute and the stoker hopper over the entire length thereof. The contents of the box compartments rested on the coal already in the stoker hopper and flowed from the compartments into the hopper wherever there was room for the coal to sink in. This method has the disadvantage that the box must be dragged through the coal so to speak and that the pressure of the column of coal extending from the discharge chute down through the box into the stoker hopper must be absorbed by the travelling grate and moreover by only a small portion thereof.

In another apparatus which has been developed in an attempt to distribute the coal evenly and uniformly across the stoker width the above difiiculty is overcome by the use of a conveyor belt running back and forth across the width of the stoker and situated between the coal discharge chute and the stoker hopper. In this manner the coal column of the discharge chute is carried by the conveyor belt and the coal is permitted to run off in a free fall in a relatively thin layer across the width of the stoker hopper. The pressure of the coal column on the conveyor belt however has caused considerable mechanical difficulties in installations of this type.

Other similar devices have been employed utilizing 2,873,037 Patented Feb. 10, 1959 ice type becomes too bulky and requires a space for opera- 7 hopper which table is equipped at its ends with two pairs of wheels or sprockets to form a trolley which rides on at least one, preferably both, of the lateral lower runs of an endless chain drag conveyor while the upper run thereof is pulled over the surface of the table.

A primary object of the invention accordingly is to provide an apparatus for distributing divided material of different sizes such as coal, for example, uniformly andevenly both as to quantity as well as particle size across the length of a given path such as the width of a travelling grate stoker.

Another object of the invention is to provide an improved distributing deviceof the endless chain conveyor variety for feeding coal to a stoker hopper in which the column of coal being fed to the hopper is carried by a table and not by the conveyor and which requires a space for operation only approximately as wide as the stoker.

Additional objects of the invention will appear from the following description of one preferred embodiment of the invention as illustrated by the accompanying drawings, wherein:

Fig. 1 is a vertical cross section through the apparatus and stoker front end.

Fig. 2 is a longitudinal section through the apparatus and taken at line 2-2 of Fig. 1.

In the illustrative embodiment shown the travelling grate S is provided in the usual manner with a stoker hopper 1 extending over the entire width of the travelling grate S and receiving fuel from a bunker 2 arranged preferably centrally to the furnace and discharging said fuel into the stoker hopper 1 by means of a chute 3. The coal from hopper 1 is deposited upon the travelling grate in a fuel layer 4, as shown in Fig. 1. The thickness of this fuel bed is determined by a gate 5 which can be raised or lowered to suit the amount of coal to be burned upon the grate.

The herein disclosed improved distributing device is arranged above the stoker hopper 1 and below the discharge funnel 3. The device comprises a trolley T including a table 6 which is supported by two web plates 7. There are mounted in the web plates 7 two axles 8 and 9. Axle 8 is provided at its ends with sprocket wheels 10. Similar sprocket wheels 10 are mounted on at the ends of axle 9. There is also provided a Worm gear 11 mounted on axle 9 and driven by a worm 12 and a gear train 13 and motor 14. In the preferred embodiment herein shown the drive mechanism including the motor is mounted on a plate 18 which is fastened to the web plates 7. The upper run of an endless chain drag conveyor C is arranged to move over the surface of the table 6.

This endless conveyor C is provided with two sprocket chains having links 15 joined by roller 16 engaging sprockets 10 and 10. The chains are spaced apart by cross members 17 which act as scrapers at the same time. At 19 the lower run of the chain drag may be fastened to the stoker hopper 1 which is provided with rails 20 upon which the rolls 16 of the 'lower run of the chain drag rest. These rails are fastened to the rim of the stoker hopper 1 and extend over the entire length thereof.

In the illustrated embodiment of my distributor device the fuel descending from bunker 2 and discharge chute 3 is supported by table 6. In operation electric power is supplied to motor 14 which drives sprocket wheels by means of axle 9, worm gear 11 and worm 12 and gears 13. In this manner sprockets 10' and 10 engaging rollers 16 of the lower run of the chain drag move towards the right causing the upper run of the chain drag to slide forward upon the table also towards the right. table or trolley as driven by the motor proceeds at a given speed then the upper run of the chain drag will move across the table at the same speed relative to the table surface or at an actual speed which is twice as fast as that of the table. As the table travels across the dis- I charge funnel 3 coal is deposited between the spacer members 17 of the upper run of the chain drag conveyor and is scraped off the right hand end of table 10 into the hopper below. As the trolley continues on its way the lower run of the conveyor will move around sprocket 10 and become the upper run of the endless chain conveyor C continuing in this manner until the table reaches the right hand end of the stoker hopper. In this manner the right hand half of the hopper is supplied with coal uniformly and evenly. Control devices well known in the art and not shown then cause the mot-or 14 to reverse its rotation and move the trolley T in the opposite direction from the right hand end to the left hand end of the stoker hopper, thereby distributing the coal uniformly and evenly over the left hand half of the hopper. In this manner the table 6, which is approximately one-half of the length of the stoker width, travels to and fro across the stoker width or length of stoker hopper 1 covering the full length thereof and distributing the coal evenly and uniformly across the width of the travelling grate stoker. In the preferred embodiment shown in Figs. 1 and 2 the driving mechanism is located and mounted below the table 6. The invention of course may also be practiced by employing a rack and pinion drive arranged along the side of the trolley.

From the above it can be seen that the herein disclosed device enables the operator to uniformly fill the right hand half of the stoker hopper with coal both as to quantity as well as to particle size while the trolley T proceeds to advance over the right hand half of the hopper and, upon automatic or manual reversal of the motor rotation, to uniformly fill the left hand half of the stoker hopper with fuel as the trolley proceeds to advance over the left hand half of the hopper. Accordingly the only space required for the operation of my inventive distributing device is that within the approximate stoker width. By the use of suitable feeler and switch devices well known in the art and not shown the feeding of the device by travelling back and forth can be stopped or set in operation when the level of the fuel in the stoker hopper reaches or recedes beyond a predetermined point.

The novel feeding and distributing device as described hereinabove also can find practical use in feeding and distributing divided material other than coal, such as sand, ores, grains, etc.

While the preferred embodiment of the invention has herein been shown and described it will be understood that changes in construction, combination and arrangement of parts may be made without departing from the spirit and scope of the invention as claimed.

What I claim is:

1. In apparatus for distributing divided material substantially uniformly along a path of given length, the combination of an endless chain drag conveyor arranged parallel and above said given path and having an upper run and a lower run; a movable table positioned below said upper run in contacting and supporting relation If the therewith and being movably supported by said lower run, the length of said table extending over at least half of the length of said path; means for anchoring said lower run at a point intermediate the ends of said path; driving means for simultaneously moving said table and the upper run of said chain drag to and fro in direction of said given path at respective velocities having a ratio of 1:2; means for feeding material onto said table at a point approximately midway of the length of said path; and means associated with said conveyor chain for pushing off said material over the downstream end of said conveyor in the material flow sense while said table advances in said downstream direction.

2. Apparatus as defined in claim 1 in which said table is provided with guide means at each end adapted to assist said chain drag in the transition from the upper run to the lower run and from the lower run to the upper run.

3. Apparatus as defined in claim 2 wherein said guide means comprise at least one sprocket drivingly engaging said chain drag conveyor and said table, and driving means for driving said sprocket.

4. Apparatus as defined in claim 3 wherein said driving means are positioned underneath and supported by said table and between said upper and lower runs.

5. Apparatus as defined in claim 1 wherein said table is an integral part of a trolley having two pairs of sprockets engaging both the upper and the lower run of said chain drag conveyor and riding on the lower run.

6. Apparatus according to claim 5 in which said driving means comprise reversible motor means operatively engaging at least one of said pairs of sprockets.

7. In apparatus for distributing divided material substantially uniformly along a path of given length, the combination of a movable table extending over said path at least half the length thereof and havinga narrow width with respect to its length; an endless chain drag conveyor having an upper run and a lower run, the inside surface of the upper run arranged to rest upon or glide over said table in a direction parallel to said path and covering the entire length of the table; two pairs of sprockets drivingly engaging said endless chain drag conveyor, each pair having an axis for rotation in a plane parallel to said given path and being rotatably mounted below and on said table, one pair adjacent each end thereof in fixed supporting relation therewith; a track having an upper surface for supporting said table and material by way of said sprocket and said lower run; and driving means for moving said table, said sprockets and said upper run to and fro upon said track and parallel to said given path, said driving means being located between said upper and lower runs and being supported in fixed relation with respect to said table and said sprockets.

8. Apparatus according to claim 7 in which said chain drag includes means for anchoring said'lower run at a point approximately midway between the ends of said given path.

9. Apparatus according to claim 8 in which said chain drag includes transverse members integral with said conveyor, spacedly arranged along the length thereof and extending across at least a major portion of said tables width.

References Cited in the file of this patent UNITED STATES PATENTS 739,161 Fisher Sept. 15, 1903 799,584 White Sept. 12, 1905 1,398,047 Stevens Nov. 22, 1921 2,018,360 Heintges Oct. 22, 1935 2,165,641 Mattox July 11, 1939 2,699,878 Avery Jan. 18, 1955 

